Diferencia entre revisiones de «Myxedema coma»

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==Background==
==Background==
#Hypothyroidism + mental status changes/coma + hypothermia + precipitating stressor
*Extreme, decompensated [[hypothyroidism]] with end-organ dysfunction
##80% mortality
*'''True endocrine emergency''' with mortality '''30-60%''' even with treatment<ref>Ono Y, et al. Clinical characteristics and outcomes of myxedema coma: analysis of a national inpatient database in Japan. ''J Epidemiol''. 2017;27(3):117-122. PMID 28142035</ref>
#Occurs in 0.1% of patients with hypothyroidism
*Misnomer: patients are not always comatose and myxedema is not always present
*Most common in elderly women with undiagnosed or undertreated hypothyroidism
*Precipitants:
**Infection/[[sepsis]] (most common trigger)
**Cold exposure, [[hypothermia]]
**Medication non-compliance with levothyroxine
**Surgery, trauma, [[MI]], [[stroke]]
**Medications: amiodarone, lithium, sedatives, opioids, anesthetics
**Adrenal crisis (concurrent [[adrenal insufficiency]])


==Precipitants==
==Clinical Features==
#Infection
*'''Classic triad''': altered mental status + hypothermia + precipitating event
##Bradycardia and hypothermia may mask usual signs of fever
*'''Altered mental status''': confusion, lethargy, obtundation → '''coma'''
#Cold exposure
*Hypothermia (may be severe, <32C; absence of fever despite infection is classic)
#Trauma
*Bradycardia and hypotension (refractory to vasopressors until thyroid hormone replaced)
#MI
*Hypoventilation with [[hypercapnia]] and [[hypoxia]] (respiratory failure)
#CHF
*Hyponatremia (due to decreased free water excretion — [[SIADH]]-like)
#CVA
*Hypoglycemia (concurrent [[adrenal insufficiency]] or hepatic dysfunction)
#GI bleed
*Non-pitting edema (myxedema), periorbital swelling
#Metabolic conditions (hypoxia, hypercapnia, hyponatremia, hypoglycemia)
*Delayed deep tendon reflexes (hung-up reflexes)
#Burns
*Ileus, urinary retention, [[hypothermia]]
#Meds: B-blockers, sedatives, narcotics, phenothiazine, amiodarone
*Pericardial effusion (may rarely cause tamponade)
#Medication non-compliance (thyroid meds)


==Diagnosis==
==Differential Diagnosis==
#Hypothermia
*[[Sepsis]] (most common precipitant AND mimic)
##So common in myxedema that a normal temperature should suggest an underlying infection
*[[Hypothermia]] (primary environmental)
##Absence of shivering distinguishes from accidental hypothermia
*[[Adrenal crisis]]
#Cardio
*[[Stroke]] / intracranial pathology
##Bradycardia
*Drug overdose (opioids, sedatives)
##Hypotension
*[[Hypoglycemia]]
#Pulm
*[[Heart failure]]
##Hypoventilation -> respiratory collapse
###CO2 narcosis
##Pleural effusions
##Upper airway obstruction from glottic edema, vocal cord edema, and macroglossia
#Neuro
##AMS/coma


==Work-Up==
==Evaluation==
#Chemistry
*TSH: markedly elevated in primary hypothyroidism (most common)
#CBC
**May be low/normal in central (pituitary/hypothalamic) hypothyroidism
#TSH, FT4, FT3
*Free T4: very low or undetectable
#Cultures
*Free T3: low (but less reliable)
#LFT
*BMP: [[hyponatremia]] (present in ~50%), [[hypoglycemia]]
#Cortisol level  
*CBC: may show anemia, leukopenia
#VBG
*ABG/VBG: respiratory acidosis, hypercapnia, hypoxemia
#CXR  
*Cortisol level (before starting steroids) — rule out concurrent adrenal insufficiency
#EKG
*Lactate: if concern for sepsis
*ECG: [[bradycardia]], low voltage, prolonged QT, possible J (Osborn) waves
==DDx==
*CXR: cardiomegaly (pericardial effusion), pleural effusion
#Sepsis
*Infectious workup: blood/urine cultures, CXR (infection is most common precipitant)
#Depression
#Adrenal crisis
#CHF
#Hypoglycemia
#CVA
#Hypothermia
#Drug overdose
#Meningitis


==Treatment==
==Management==
#Supportive care
===Immediate===
##Respiratory distress
*'''Airway management''': intubation for respiratory failure or severe AMS
###Mechanical ventilation if needed
*Passive rewarming (avoid active external rewarming which can cause vasodilation and cardiovascular collapse)
##Hypoglycemia
*IV access, cardiac monitoring
###IV dextrose
*Treat precipitant (antibiotics for suspected infection, dextrose for hypoglycemia)
##Hyponatremia
 
###Water restriction
===Thyroid Hormone Replacement===
##Hypotension
*IV levothyroxine (T4) is the mainstay:
###Vasopressors (ineffective w/o thyroid hormone replacement)
**Loading dose: 200-400 mcg IV (or 4 mcg/kg lean body weight)
###Hydrocortisone 100mg q8hr IV (adrenal insufficiency may also be present)
**Then 50-100 mcg IV daily
####Give first dose before starting thyroid replacement therapy
*IV liothyronine (T3) may be added for severe cases:
##Hypothermia
**5-20 mcg IV loading dose, then 2.5-10 mcg IV q8h
###Treat w/ passive rewarming (active rewarming may cause hypotension)
**T3 has faster onset of action (~4 hours vs 24 hours for T4)
#Thyroid replacement therapy
**Use with caution in elderly / cardiac patients (arrhythmia risk)
##Optimal regimen is controversial
*'''Route must be IV''' — GI absorption unreliable due to ileus and mucosal edema
##Can give T3 or T4 or both
 
##T4
===Stress-Dose Steroids===
###Advantages
*Hydrocortisone 100 mg IV q8h — give BEFORE or concurrent with thyroid hormone<ref>Jonklaas J, et al. Guidelines for the treatment of hypothyroidism. ''Thyroid''. 2014;24(12):1670-1751. PMID 25266247</ref>
####Smooth, slow steady onset of action
*Rationale: thyroid hormone replacement increases cortisol metabolism; if concurrent adrenal insufficiency exists, this can precipitate [[adrenal crisis]]
####May be safer in pts with CAD
*Discontinue steroids once adrenal insufficiency ruled out
###Disadvantages
 
####Requires extrathyroidal conversion of T4 -> T3 to work (may be reduced in myxedema)
===Supportive Care===
###Dose: Start 4mcg/kg IV followed by 100mcg IV in 24hr
*Fluid restriction if severe [[hyponatremia]] (dilutional)
##T3
*Avoid hypotonic fluids (worsens hyponatremia)
###Advantages
*Cautious IV NS for hypotension
####Does not require extrathyroidal action to work
*Vasopressors may be needed but often refractory until thyroid hormone takes effect
####Rapid onset of action
*Avoid sedatives and opioids (impair respiratory drive)
###Disadvantages
*Electrolyte correction (hyponatremia, hypoglycemia)
####Rapid onset of action (may not be desirable in pts w/ CAD)
###Dose: 20mcg IV followed by 10mcg q8hr until pt is conscious
####Start with 10mcg if elderly or has CAD
#Treaty precipitating factors


==Disposition==
==Disposition==
#Admit to ICU
*ICU admission for all patients
#Endocrine consult
*Serial monitoring: TSH, free T4, electrolytes, glucose, cortisol
*Improvement in vital signs expected within 24-48 hours
*Mental status may take '''days to weeks''' to normalize
*Long-term oral levothyroxine replacement once stabilized


==See Also==
==See Also==
*[[Hypothyroidism]]
*[[Hypothyroidism]]
*[[Thyroid (General)]]
*[[Thyroid storm]]
*[[Adrenal insufficiency]]
*[[Hypothermia]]
*[[Hyponatremia]]


==Source==
==References==
Tintinalli's
<references/>
*Mathew V, et al. Myxedema coma: a new look into an old crisis. ''J Thyroid Res''. 2011;2011:493462. PMID 22028977
*Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies. ''Med Clin North Am''. 2012;96(2):385-403. PMID 22443982
*Wall CR. Myxedema coma: diagnosis and treatment. ''Am Fam Physician''. 2000;62(11):2485-2490. PMID 11130234


[[Category:Endo]]
[[Category:Endocrinology]]
[[Category:Critical Care]]

Revisión actual - 09:28 22 mar 2026

Background

  • Extreme, decompensated hypothyroidism with end-organ dysfunction
  • True endocrine emergency with mortality 30-60% even with treatment[1]
  • Misnomer: patients are not always comatose and myxedema is not always present
  • Most common in elderly women with undiagnosed or undertreated hypothyroidism
  • Precipitants:
    • Infection/sepsis (most common trigger)
    • Cold exposure, hypothermia
    • Medication non-compliance with levothyroxine
    • Surgery, trauma, MI, stroke
    • Medications: amiodarone, lithium, sedatives, opioids, anesthetics
    • Adrenal crisis (concurrent adrenal insufficiency)

Clinical Features

  • Classic triad: altered mental status + hypothermia + precipitating event
  • Altered mental status: confusion, lethargy, obtundation → coma
  • Hypothermia (may be severe, <32C; absence of fever despite infection is classic)
  • Bradycardia and hypotension (refractory to vasopressors until thyroid hormone replaced)
  • Hypoventilation with hypercapnia and hypoxia (respiratory failure)
  • Hyponatremia (due to decreased free water excretion — SIADH-like)
  • Hypoglycemia (concurrent adrenal insufficiency or hepatic dysfunction)
  • Non-pitting edema (myxedema), periorbital swelling
  • Delayed deep tendon reflexes (hung-up reflexes)
  • Ileus, urinary retention, hypothermia
  • Pericardial effusion (may rarely cause tamponade)

Differential Diagnosis

Evaluation

  • TSH: markedly elevated in primary hypothyroidism (most common)
    • May be low/normal in central (pituitary/hypothalamic) hypothyroidism
  • Free T4: very low or undetectable
  • Free T3: low (but less reliable)
  • BMP: hyponatremia (present in ~50%), hypoglycemia
  • CBC: may show anemia, leukopenia
  • ABG/VBG: respiratory acidosis, hypercapnia, hypoxemia
  • Cortisol level (before starting steroids) — rule out concurrent adrenal insufficiency
  • Lactate: if concern for sepsis
  • ECG: bradycardia, low voltage, prolonged QT, possible J (Osborn) waves
  • CXR: cardiomegaly (pericardial effusion), pleural effusion
  • Infectious workup: blood/urine cultures, CXR (infection is most common precipitant)

Management

Immediate

  • Airway management: intubation for respiratory failure or severe AMS
  • Passive rewarming (avoid active external rewarming which can cause vasodilation and cardiovascular collapse)
  • IV access, cardiac monitoring
  • Treat precipitant (antibiotics for suspected infection, dextrose for hypoglycemia)

Thyroid Hormone Replacement

  • IV levothyroxine (T4) is the mainstay:
    • Loading dose: 200-400 mcg IV (or 4 mcg/kg lean body weight)
    • Then 50-100 mcg IV daily
  • IV liothyronine (T3) may be added for severe cases:
    • 5-20 mcg IV loading dose, then 2.5-10 mcg IV q8h
    • T3 has faster onset of action (~4 hours vs 24 hours for T4)
    • Use with caution in elderly / cardiac patients (arrhythmia risk)
  • Route must be IV — GI absorption unreliable due to ileus and mucosal edema

Stress-Dose Steroids

  • Hydrocortisone 100 mg IV q8h — give BEFORE or concurrent with thyroid hormone[2]
  • Rationale: thyroid hormone replacement increases cortisol metabolism; if concurrent adrenal insufficiency exists, this can precipitate adrenal crisis
  • Discontinue steroids once adrenal insufficiency ruled out

Supportive Care

  • Fluid restriction if severe hyponatremia (dilutional)
  • Avoid hypotonic fluids (worsens hyponatremia)
  • Cautious IV NS for hypotension
  • Vasopressors may be needed but often refractory until thyroid hormone takes effect
  • Avoid sedatives and opioids (impair respiratory drive)
  • Electrolyte correction (hyponatremia, hypoglycemia)

Disposition

  • ICU admission for all patients
  • Serial monitoring: TSH, free T4, electrolytes, glucose, cortisol
  • Improvement in vital signs expected within 24-48 hours
  • Mental status may take days to weeks to normalize
  • Long-term oral levothyroxine replacement once stabilized

See Also

References

  1. ↑ Ono Y, et al. Clinical characteristics and outcomes of myxedema coma: analysis of a national inpatient database in Japan. J Epidemiol. 2017;27(3):117-122. PMID 28142035
  2. ↑ Jonklaas J, et al. Guidelines for the treatment of hypothyroidism. Thyroid. 2014;24(12):1670-1751. PMID 25266247
  • Mathew V, et al. Myxedema coma: a new look into an old crisis. J Thyroid Res. 2011;2011:493462. PMID 22028977
  • Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies. Med Clin North Am. 2012;96(2):385-403. PMID 22443982
  • Wall CR. Myxedema coma: diagnosis and treatment. Am Fam Physician. 2000;62(11):2485-2490. PMID 11130234
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